Electric signal-receiving appliance.



J. G. MITCHELL. ELECTRIG SIGNAL RECEIVING APPLIANCE.

APPLICATION FILED JULY26,1907

Patented May 21, 1912 l with combined te BEST A AILABLE CQPY say-G7 MITCHELL; or QLE ELA DL 0. 110 esamee TH NORTH, ELECTRIC '3 omer-711m r CL V AND H A CQBPOBATIQWQF OH O- citizen of the United States of Amerit-a,and

a resident of (levelainL in the county of (u ahoga and State of Ollie, have inyent ed' eertain new and useful Ilnproveinents. in Eltlie. Signal-Reeeiving "Ap p liam'eg ot whit-h the follmxing is a sp azilieatiol My invention relates to in provements in sigi'ial-reeeiying appliant'fes, and n'tore partieulai-ly to those employed in eonneetitm 'a'phie and telephonic syste nn'; although my said immovements are'not neeessarily restrieted thereto in their empleyment'. In sueh eethhined systems, a l 'O-littldtl v senaitlye signal-reeeivtng appl anre ist desirahle, if not necessary, but such strument.

appliance .(ilJYiUtlHly must he capable of atl ordi ng a sufiieiently loud signal tie-die heard'muler ordinary eonditions,- ata (ensiderahle distance from the telephone in- Ordinarily the signal must he diam-11m and nn rlied in order to he pragtieal'. The usual mode of transmitting such Sign: la is to impress upon the eonneeted eireuit, an alternating current which will most strongly afl'ert the signal-reeeiver but hecause of adverse conditions and relatively long and poorly constructed lines, I have found that ordinary in ansare not adequate for giving the required signal. Accordinglygl have adapted the general type oi telephone reeeirer, as the most sensitive and pnaetie'atinatrument tor trl inslating Sllt'li alt'ernating eurrents into. the required signal, and have modified and jinilnioyetl such tele phone reeeirei" in the manner hereiuafl ter pointed out and el: med, Wittl'tltf the signal tliere'firo n is a nut itied, and the :eijlieienoy of the instrl unent is gmeat impiieved;

ll wietly stated, the ;p.i :t'er1:ed vemhQdjinlent lllYQlltltXlt. ,eonipi'ises ;a telephone rex-vheimii-n t' he eleetronn net made adjustabletoward and from the vibratory dia iplnagm. Assoeiateil with said alia- .dhra 'm is a shallow ,soimd .chamher and a trumpet.- ()11m0tt'lll piece for amplitying the sound. The sound -Qltflj1'llJQl' as most am' ply ai nl;,(:l'iea1' ly formed ivy-means 0f airammlar anemher resting upon the main diaphragm of'tthe ITGCGHFQlf flJId a per'forated diaphri gm (ta-ruled thereby in .elose ,pr oxin'r y to the torn ler, and having a centrally 'mounted trumpet extending therefrom.

Further details of construction will. be

Speqifieatilqnqf l ettersl ate nf i ati n t a. my- 2 20,7. vserial as emit-i mcee-m smNA -Imomvmer APPLIANCE.

lfat ented lliay 21.

more readily gathered by making referenee to the aeconuianying sheetof drawings and the specifications ex 'ilanat'ory thereof.

I igure I of said drawings isia View in side e tion of the pa, lred einlnnlilnent.

elf my lnyei ition. Fig. I1 is a Viewpartialty in vertical section thereof. Fig. In i3, :1

detail in section, showing: the electro inagnet and adjusting means of the appliance. Fig. IV is a trz u m'erse eeetional ieu on line 4V, If" 1i. Fig-ail is a top View of the device and Fig. VT a detail shutting the per'lo-eated supplemental diaphragm and a portion of the associated horn (iii mouth piece.

the draw ngs l have indicatedsimilar parts by the game enaraeter oi ie t'erenee.

lnas n n eh a the structure follows elosely upon. the lines of gsogil iitri'eial telephone reeeiv extended explanation will not be neemary. In n improved deviiee. the permaiient magnet 7) momita the soft iron pole pieees e e" of the electe -magnet e whose indinge; are eonneeted with the conducting- (20rd e for attaehnient to the exeiting ring-nit. Between the extended poles of the aelectre magniel} and the limbs of the permanent magnet. is nmunted a double segmental threaded memher r by means of a transverse screw 2 'lln'nugh longitudinal openings in thememl ier 1' ex tend the insulated eonduetors e p which mute the eonduetmg eerd with the windings o:l' the eleetro-inaguet. A hell-shapedeup 5,

preferably formed of a relatiyely heavy ranting, is threaded upon the memher '13, hile a 'loelmiut n, is diapi ised in nnecliately, beneath mid cup, to retain the parts in their [)(isitioHS-Qf :ltlj'ttHtJl'lQlll. lhese members oh- .iiieusly -ahmlld he 't'orn ed of min-magnetic metals to a'qoid ,elosing the magnetic lines v f force. ltfiitiOllPfl upon the annular rim of .eu-p is the "magnetiediaphragm (Z, respol isive to currents flow? in ,tlie electroana gnetje. associated n iths aid diaphragm iS til lQ sound hamlier,-\vhie i is tried-readily and ,eheaply forn'ied by means of an annular fiber washer or spa ting: melnher er, and the supplementany (liapl ii'a g'nr (l' raiperposed thereon clone y adjacent to diaphragm d. The .aupplenient-ary diaphragm ha its center perforated, and-attaehed thereto the horn or month piece on, the outer opening 01- nhich preferably is closed by means of secured in plaee- 'lhroughout each of the several fignrea of wire gauze m. Securing the diaphragms together, and. completing the sound chamber, is the threaded annulus '2", wherein is screwed the cup I), which retains the diaphragms perip rally in close proximity, while permitting maximum vibration at their centers.

From the construction described, it will be seen that the poles of the elect'ro-magnet are adjustable toward and from the main diaphragm d, to insure the highest efficiency or response for any given current impressed HPOAIQ; the line. By reason of theurelat ively heavy castings forming the bell and annu- F has, the sound chamber is so mounted as to augment the effect of the electro-magnet,

"while the trumpet or mouthpiece, not only serves to transmit the vibrations from the main diaphragm and sound chamber and give direction thereto, but greatly increases the surface of thesupplementary diaphragm, which is set into vibration through the medium of the air within the shallow sound chamber. In consequence, the instrument described is adapted greatly to augment the sound-producing effect of currents trans protected opening of the trumpet or mouth piece registering with a corresponding opening in the casing o of the telephone instrument, yet wholly free and unimpeded in its vibrations. Serving as it'does to increase the vibratory body or surface of the supplemental diaphragm and sound chamber, the horn or mouth piece materially augments the volume of the signal produced, but ohviously the same may be dispensed with, if

desired.

The preferred signal is one produced by alternating currents, small in quantity, and

of such frequency as will not affect relays or other'telegraph instruments connected upon theline. The signal produced resemloles the tone of a comet, which may be heard in a large room ata considerable distance from the telephone, and is so distinctive as to overcome ordinary sounds, such as those of telegraph instruments or passing trains,

for example, andthereby the telephone instrument.

call the party to While I have described the preferred c011- struction of my'improved signal-receiver and its customary employment, I do not wish to be understood as limiting the. same either to such construction ,or use, further than is to be properly inferred from the appended claims, and

I desire to secure by Letters Patent, the

following I 1. In a device of the class described, the combination with an electro-magnet, of a vibratory sound chamber comprising a main and a perforated diaphragm positioned closely adjacent to each other, a horn directly attached at the opening within the latter and supported in position freely to vibrate, a relatively massive anchorage annularly' engaging the diaphragms, and means for securingthe adjustment of the electro-magnet with relation to the sound chamber, substantially as set forth.

2. In an electro-magnetic receiver, the combination with permanent and electromagnets, of a vibratory diaphragm positioned before the electro-magnet, a supple mentary diaphragm, an interposed member forming a shallow sound chamber, and a horn or mouth p'iece directly engaging a wall of the sound chamber thus formed, sub stantially as set forth. I

3. In .a device of the .class described, the combination with permanent and electromagnets, of a vibratory diaphragm positioned before the electro-niagnet, a supplementary diaphragm, having a c'entralopening, a horn or mouth piece secured thereto at said opening, and an annular member interposed between the two diaphragmsandthereby se rving to form a shallow sound chamber, substantially as set forth. 4 L

4:. The combination with a permane'ntv magnet, of an.a'ssociated elect-ro-magnet, a threaded member between the poles thereof, a relatively heavy hell or cup into which the threaded member isscrewed, amagnetic diaphragm, an annular spacing member,

and a perforated supplemental diaphragm superposed, andrestmg upon the rim of the bell, an annulus securing said parts together, and a horn or mouth piece associated with the supplemental diaphragm and supported in position freely tovibrate, substantially as set forth.

Signed at Cleveland, this 22nd day of July,

A, D. 1907, in theprescnce of two subscribing witnesses.

JAY e. MITCHELL. [1 s] VVit nesses:

V. ti. AnMsrRoNo, ALBERT LYNN LAWRENCE. 

